CANTHAXANTHIN
Prepared at the 51st JECFA (1998), published in FNP 52 Add 6 (1998)
superseding specifications prepared at the 44th JECFA (1995), published in
FNP 52 Add 3 (1995). ADI 0-0.03 mg/kg bw, established at the 44th JECFA in
1995.
SYNONYMS CI Food Orange 8; INS No. 161 g; CI (1975) No 40850
DEFINITION Consists predominantly of trans-ß-carotene-4,4'-dione together with minor
amounts of other isomers; diluted and stabilized forms are prepared from
canthaxanthin meeting these specifications and include solutions or
suspensions of canthaxanthin in edible fats or oils, emulsions and water
dispersible powders; these preparations may have different cis/trans isomer
ratios; the analytical methods described for the parent colour are not
necessarily suitable for the assay of or determination of impurities in the
stabilized forms (appropriate methods should be available from the
manufacturer).
These specifications define only synthetic canthaxanthin and do not cover any
commercially available food colour from natural sources.
Chemical names ß-Carotene-4,4'-dione; canthaxanthin; 4,4'-dioxo-ß-carotene
C.A.S. number 514-78-3
Chemical formula C40H52O2
Structural formula
Formula weight 564.86
Assay Not less than 96% of total colouring matters (expressed as canthaxanthin)
DESCRIPTION Deep violet crystals or crystalline powder; sensitive to oxygen and light and
should therefore be kept in a light-resistant container under inert gas
FUNCTIONAL USES Colour
CHARACTERISTICS
IDENTIFICATION
Solubility (Vol. 4)
Insoluble in water, insoluble in ethanol, practically insoluble in vegetable oils,
very slightly soluble in acetone
Spectrophotometry
(Vol. 4)
A solution in cyclohexane has an absorbance maximum between 468 and 472
nm
Positive test for
carotenoids
The colour of a solution of canthaxanthin in acetone disappears after
successive additions of a 5 % solution of sodium nitrite and 1 N sulfuric acid
PURITY
Sulfated ash (Vol. 4)
Not more than 0.1%
Test 2 g of the sample (Method I)
Subsidiary colouring
matters
Carotenoids other than canthaxanthin: not more than 5% of total colouring
matters
See description under TESTS
Lead (Vol. 4) Not more than 2 mg/kg
Determine using an atomic absorption technique appropriate to the specified
level. The selection of sample size and method of sample preparation may be
based on the principles of the methods described in FNP 5, “Instrumental
Methods”.
TESTS
PURITY TESTS
Subsidiary colouring
matters
Dissolve about 80 mg of sample in 100 ml chloroform. Apply 400 µl of this
solution as a streak 2 cm from the bottom of a TLC-plate (Silicagel 0.25 mm).
Immediately develop the chromatogram with a solvent mixture of 95 parts
dichloromethane and 5 parts diethyl ether in a saturated chamber, suitably
protected from light, until the solvent front has moved 15 cm above the initial
streak. Remove the plate, allow the main part of the solvent to evaporate at
room temperature and mark the principal band as well as the bands
corresponding to other carotenoids. Remove the silicagel adsorbent that
contains the principal band, transfer it to a glass-stoppered 100 ml centrifuge
tube and add 40.0 ml chloroform (solution 1).
Remove the silicagel adsorbent that contains the combined bands
corresponding to the other carotenoids, transfer it to a glass-stoppered, 50 ml
centrifuge tube and add 20.0 ml chloroform (solution 2).
Shake the centrifuge tubes by mechanical means for 10 min and centrifuge for
5 min. Dilute 10.0 ml of Solution 1 to 50.0 ml with chloroform (solution 3).
Determine, with a suitable spectrophotometer, the absorbances of Solutions 2
and 3 in 1-cm cells at the wavelength maximum about 485 nm, using
chloroform as blank.
Calculation
Carotenoids other than canthaxantin (%) =
where
A2 = absorbance of Solution 2
A3 = absorbance of Solution 3
METHOD OF
ASSAY
Proceed as directed under Total Content by Spectrophotometry (see Volume
4) using the following conditions:
W = 0.1 g
V1 = V2 = V3 = 100 ml
v1 = v2 = 5 ml
A1%1 cm = 2200
wavelength max = about 470 nm
CANTHAXANTHIN
SYNONYMS
DEFINITION
Chemical names
C.A.S. number
Chemical formula
Structural formula
Formula weight
Assay
DESCRIPTION
FUNCTIONAL USES
CHARACTERISTICS
IDENTIFICATION
Spectrophotometry
Positive test for carotenoids
PURITY
Subsidiary colouring matters
Lead (Vol. 4)
TESTS
PURITY TESTS
Subsidiary colouring matters
METHOD OF ASSAY